Launch vehicle payload chambers often carry satellites. Prior to launch, it is important to keep satellite components below critical temperatures. In order to accomplish this goal, an external supply of cool air is usually pumped through the launch vehicle payload chamber. In order to prevent "hot spots," the cool air must be evenly distributed throughout the launch vehicle payload chamber. At the same time, the satellite must be protected from high velocity air, which could damage the satellite. During launch, the air supply is disconnected and other cooling mechanisms are employed.
One approach to cooling a payload chamber prior to launch has been to use an air jet or nozzle mounted at various locations and pointed towards an inner wall of the payload chamber. This approach suffers from at least two main problems. First, the airflow from the nozzle is unevenly distributed throughout the payload chamber. Additionally, cantilevered components must be used to mount the nozzle within the payload chamber, adding unnecessary weight and thus increasing power requirements.
A second approach has been to use a flat plate mounted above the satellite that is carried by the payload chamber. The plate acts as a velocity reducing chamber and also contains holes to permit some of the cooling air to flow through it. This approach also suffers from problems. First the determination of the size and placement of the holes in the plate is complicated especially when trying to design a plate which performs well under varying flow conditions. Second, the plate spans and is secured across a break joint where the payload chamber opens to release the satellite it is carrying, creating a significant risk of damage to the satellite upon release. Finally, the plate is difficult to mount and support within the payload chamber due to the intense forces the plate experiences during launch.
A third approach has been to use an annulus. Unfortunately, an annulus also suffers from problems similar to those noted above. First, the annulus spans and is secured across the break joint. Additionally, the annulus is fairly heavy, thus increasing the launch vehicle power requirements. Finally, it is difficult to determine where to position holes in an annulus so that the cooling air is adequately distributed.
Therefore, there is a need for a launch vehicle payload chamber cooling system that evenly distributes cooling air and is lightweight and reliable.